Radio Frequency Identification devices (“RFID tags”) are known in the art and used for many purposes, including article control in retail stores and warehouses, electronic toll collection and tracking of freight containers. In many cases, the RFID tag is powered only by the electromagnetic energy from the radio signal sent by an interrogation device or “tag reader.” Thus, when the tag is not being read, it is not possible for the tag electronics to perform any functions unless the tag is also battery powered. Battery power is not an option in many cases for reasons such as cost, size and reliability.
It is known in the art to provide RFID tags with non-volatile memory for storage of information that the user or the tag issuing entity may need to change during the tag's lifetime. Changing or writing data to the non-volatile memory such as an EEPROM requires that the tag be powered. One application for the use of non-volatile memory in an RFID tag is to record events in the tag's environment, such as temperature, shock and vibration, to record the environment to which the object that the tag is associated with was subjected. Another such application is to record events that would indicate tampering with a container or packaging to which the tag is attached. For example, when sealed cargo containers, such as intermodal freight containers, are carrying finished goods or materials that need to be carefully tracked or inventoried, there is a need to record events indicating whether the container has been tampered with. In the past, such containers have been outfitted with RFID tags for tracking in and out of ports and shipping yards, but there was no connection between container seals and the RFID tag. Electronic tamper seals are known, but they have not been implemented with RFID tags so as to make evidence of tampering readily accessible by the same equipment that tracks the container.
Therefore a need exists for a vehicle RFID tag that can record events such as seal tampering while unpowered by a battery or reader signal.